'donor site' to bald or balding part of the body known as the 'recipient site'. It is primarily used to treat male
pattern baldness. In this minimally invasive procedure, grafts containing hair follicles that are genetically resistant to balding are transplanted to the bald scalp. It can also be used to restore eyelashes, eyebrows, beard hair, chest hair, pubic hair and to fill in scars caused by accidents or surgery such as face-lifts and previous hair transplants. Hair transplantation differs from skin grafting in that grafts contain almost all of the epidermis and dermis surrounding the hair follicle, and many tiny grafts are transplanted rather than a single strip of skin.
Since hair naturally grows in groupings of 1 to 4 hairs, today’s most advanced techniques harvest and transplant these naturally occurring 1–4 hair "follicular units" in their natural groupings. Thus modern hair transplantation
can achieve a natural appearance by mimicking nature hair for hair. This hair transplant procedure is called Follicular Unit Transplantation(FUT). Donor hair can be harvested two different ways: strip harvesting, and follicular unit extraction (FUE).
The use of both scalp flaps, in which a band of tissue with its original blood supply is shifted to the bald area, and free grafts dates back to the 19th century. Modern transplant techniques began in Japan in the 1930s, where surgeons used small grafts, and even "follicular unit grafts" to replace damaged areas of eyebrows or lashes, but not to treat baldness. Their efforts did not receive worldwide attention at the time, and the traumas of World War II kept their advances isolated for another two decades.
The modern era of hair transplantation in the western world was ushered in the late 1950s, when New York dermatologist Norman Orentreich began to experiment with free donor grafts to balding areas in patients with male pattern baldness. Previously it had been thought that transplanted hair would thrive no more than the original hair at the "recipient" site. Dr. Orentreich demonstrated that such grafts were "donor dominant," as the new hairs grew and lasted just as they would have at their original home.
Advancing the theory of donor dominance, Walter P. Unger, M.D. defined the parameters of the "Safe Donor Zone" from which the most permanent hair follicles could be extracted for hair transplantation. As transplanted hair will only grow in its new site for as long as it would have in
its original one, these parameters continue to serve as the fundamental foundation for hair follicle harvesting, whether by strip method or FUE.
For the next twenty years, surgeons worked on transplanting smaller grafts, but results were only minimally successful, with 2–4 mm "plugs" leading to a doll's head-like appearance. In the 1980s, Uebel in Brazil popularized using large numbers of small grafts, while in the United States Dr. William Rassman began using thousands of “micrografts” in a single session.
In the late 1980s, Dr. B.L. Limmer introduced the use of the stereo-microscope to dissect a single donor strip into small micrografts.
The follicular unit hair transplant procedure has continued to evolve, becoming more refined and minimally invasive as the size of the graft incisions have become smaller. These smaller and less invasive incisions enable surgeons to place a larger number of follicular unit grafts into a given area. With the new "gold standard" of ultra refined follicular unit hair transplantation, over 50 grafts can be placed per square centimeter, when appropriate for the patient.
Surgeons have also devoted more attention to the angle and orientation of the transplanted grafts. The adoption of the “lateral slit” technique in the early 2000s, enabled hair transplant surgeons to orient 2 to 4 hair follicular unit grafts so that they splay out across the scalp's surface. This enabled the transplanted hair to lie better on the scalp and provide better coverage to the bald areas. One disadvantage however, is that lateral incisions also tend to disrupt the scalp's vascularity more than sagittals. Thus sagittal incisions transect less hairs and blood vessels assuming the cutting instruments are of the same size. One of the big advantages of sagittals is that they do a much better job of sliding in and around existing hairs to avoid follicle transection. This certainly makes a strong case for physicians who do not require shaving of the recipient area. The lateral incisions bisect existing hairs perpendicular (horizontal) like a T while sagittal incisions run parallel (vertical) alongside and in between existing hairs. The use of perpendicular (lateral/coronal) slits versus parallel (sagittal) slits, however, has been heavily debated in patient-based hair transplant communities. Many elite hair transplant surgeons typically adopt a combination of both methods based on what is best for the individual patient.
With the latest improvements in surgical technique and especially with the FUE procedure, the recovery time is immediate and the pain negligible. There is no bed rest or hospitalization required after the hair transplant. Today 85% of hair transplants work